Joint assembly for fluid carrying pipes

ABSTRACT

A joint assembly for joining two pipes together comprises first and second liners and first and second pipe flanges. Each liner includes a sleeve and a liner flange with the liner flange coupled to one end of the sleeve. The first liner may be positioned within a first pipe and the second liner may be positioned within a second pipe. Each pipe flange includes an inner surface and an opposing outer surface with a plurality of circumferentially spaced plateaus positioned thereon. Each plateau has a height above the outer surface. The first pipe flange may be coupled to one end of the first pipe and the second pipe flange may be coupled to one end of the second pipe. The first and second pipe flanges may couple to one another such that each plateau on the first pipe flange contacts a corresponding plateau on the second pipe flange.

BACKGROUND OF THE INVENTION Field of the Invention

Embodiments of the current invention relate to joints for irrigationsystem pipes and other pipes that carry fluids.

Description of the Related Art

Fluid carrying pipes may be implemented in crop irrigation systems, gasor oil pipelines, refineries and processing plants, plumbing systems,drainage systems, and the like. Typically, the pipes are joined to oneanother to form systems that carry the fluid over great distances. Tocreate a joint between two pipes, each pipe may include a pipe flangeextending radially outward from the circumference of each end of thepipe. Each pipe may further include a pair of liners, each linerincluding a sleeve and a liner flange with the liner flange coupled toone end of the sleeve. One liner fits within each end of the pipe suchthat an inner surface of the liner flange contacts at least a portion ofthe outer surface of the pipe flange. The pipes may be joined togethersuch that the outer surface of one pipe flange may contact the outersurface of an adjacent pipe flange. Typically the one pipe flange iscoupled to the adjacent pipe flange using circumferentially-spacedfasteners such as screws which extend through both flanges to hold themtogether and form a seal between the two liner flanges.

Many prior art pipe flanges include a raised face on the outer surfacewherein an annular portion of the flange, adjacent to the innercircumference, has a height above the rest of the outer surface. Theheight differential creates a gap adjacent to the outer circumferencebetween the two pipe flanges when they are joined together. Thefasteners holding the two pipe flanges together are usually positionedcloser to the outer circumference, or radially outward from the raisedface—which means the fasteners extend from one flange to the otherthrough the gap. Coupling one pipe flange to the other across the gapmay lead to non-uniform pressure around the circumference being appliedto the seal, which may cause problems during operation of the system inwhich the pipes are utilized.

SUMMARY OF THE INVENTION

Embodiments of the current invention solve the above-mentioned problemsand other problems and provide a distinct advance in the art ofassemblies for joining two pipes together. Specifically, the currentinvention provides a joint assembly that includes first and second pipeflanges, each with a plurality of raised plateaus on an outer surface.The first and second pipe flanges couple to one another such that theplateaus on the first pipe flange contact the plateaus on the secondpipe flange. This structure provides uniform pressure on a seal formedbetween the pipes that are joined together. In addition, varying theheight of the plateaus varies the pressure on the seal.

In one embodiment, the joint assembly comprises first and second linersand first and second pipe flanges. Each liner includes a sleeve and aliner flange with the liner flange coupled to one end of the sleeve. Thefirst liner is configured to be positioned within a first pipe and thesecond liner is configured to be positioned within a second pipe. Eachpipe flange is of generally annular disc shape with an inner surface andan opposing outer surface including a plurality of circumferentiallyspaced plateaus positioned thereon. Each plateau has a height above theouter surface. The first pipe flange is configured to be coupled to oneend of the first pipe and the second pipe flange is configured to becoupled to one end of the second pipe. The first and second pipe flangesare configured to couple to one another such that each plateau on thefirst pipe flange contacts a corresponding plateau on the second pipeflange.

In another embodiment, the current invention provides a two pipeassembly comprising first and second pipes, first and second liners, andfirst and second pipe flanges. The first and second pipes are axiallyaligned with one another. Each liner includes a sleeve and a linerflange with the liner flange coupled to one end of the sleeve. Eachliner flange includes an inner surface adjacent to the sleeve and anouter surface facing away from the sleeve. The first liner is positionedwithin the first pipe, and the second liner positioned within the secondpipe. The first and second liners face each other such that the outersurface of the first liner contacts the outer surface of the secondliner to form a seal between the first pipe and the second pipe.

Each pipe flange is of generally annular disc shape with an innersurface and an opposing outer surface including a plurality ofcircumferentially spaced plateaus positioned thereon. Each plateau has aheight above the outer surface. The first pipe flange is coupled to oneend of the first pipe, and the second pipe flange is coupled to one endof the second pipe. The first and second pipe flanges are coupled to oneanother such that each plateau on the first pipe flange contacts acorresponding plateau on the second pipe flange.

Still another embodiment of the current invention provides a pipecomprising a hollow tubular section and first and second pipe flanges.Each pipe flange is of generally annular disc shape with an innersurface and an opposing outer surface including a plurality ofcircumferentially spaced plateaus positioned thereon. Each plateau has aheight above the outer surface. The first pipe flange is coupled to oneend of the tubular section, and the second pipe flange is coupled to theother end of the tubular section such that the outer surface of eachpipe flange faces away from the tubular section.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the current invention will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the current invention are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a perspective view of a joint assembly, constructed inaccordance with various embodiments of the current invention, forjoining two pipes together, the joint assembly including at least firstand second pipe flanges;

FIG. 2 is an exploded view of the joint assembly with the first andsecond pipe flanges and further including first and second liners;

FIG. 3 is a cross sectional view of the joint assembly cut along theline 3-3 of FIG. 1, illustrating the two pipes, the first and secondflanges, and the first and second liners forming a seal between thepipes;

FIG. 4 is an enlarged portion of a cross sectional view of a linerincluding a sleeve and a liner flange illustrating that the liner flangehas a thickness T;

FIG. 5 is an enlarged portion of a cross sectional view of a pipe flangeincluding an inset and a plateau, illustrating that the plateau has aheight H above an outer surface of the pipe flange;

FIG. 6 is an exploded view of a joint assembly including otherembodiments of the first and second pipe flanges;

FIG. 7 is an enlarged portion of a cross sectional view of one of thepipe flanges of FIG. 6, the pipe flange including a recess with a depthD;

FIG. 8 is an exploded view of a joint assembly including still otherembodiments of the first and second pipe flanges; and

FIG. 9 is an enlarged portion of a cross sectional view of one of thepipe flanges of FIG. 8, the pipe flange including an recess with a depthD and an inner recess.

The drawing figures do not limit the current invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following detailed description of the invention references theaccompanying drawings that illustrate specific embodiments in which theinvention can be practiced. The embodiments are intended to describeaspects of the invention in sufficient detail to enable those skilled inthe art to practice the invention. Other embodiments can be utilized andchanges can be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present invention is definedonly by the appended claims, along with the full scope of equivalents towhich such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the current technology can include a variety of combinationsand/or integrations of the embodiments described herein.

A joint assembly 10, constructed in accordance with various embodimentsof the current invention, for fluid carrying pipes is shown in FIGS.1-3. The joint assembly 10 may broadly comprise a first liner 12, asecond liner 14, a first pipe flange 16, and a second pipe flange 18.The joint assembly 10 may be implemented with pipes 20 (20A, 20B) thatare joined together to carry a large volume of fluid. Each pipe 20 isgenerally of hollow cylindrical or tubular shape with opposing open endsand may be formed from metals or plastics. Embodiments of the currentinvention are particularly suited for use with mobile irrigationsystems, but may be used with any fluid-carrying pipes.

The first liner 12 may include a sleeve 22 and a liner flange 24, asbest seen in FIG. 2. The sleeve 22 may be of hollow cylindrical ortubular shape. The liner flange 24 is attached to one end of the sleeve22 and is of generally annular disc shape with an inner surface 23 andan opposing outer surface 25. The liner flange 24 includes an inner edgeto which the sleeve 22 is attached and a radially-spaced outer edge witha plurality of circumferentially-distributed cutouts 26 formed thereon.One embodiment of the liner flange 24 includes six cutouts 26 along theouter edge spaced apart by a rotational angle of approximately 60degrees. Each cutout 26 may have a semicircular, semioval,semielliptical, or generally arcuate concave shape. The inner edge ofthe liner flange 24 is coupled to one end of the sleeve 22 along anouter circumference thereof. Furthermore, the outer surface 25 of theliner flange 24 faces away from the sleeve 22, while the inner surface23 is positioned adjacent to the sleeve 22. In some embodiments, thefirst liner 12 may be of monolithic construction with the sleeve 22 andliner flange 24 forming a single piece. In other embodiments, the sleeve22 and the liner flange 24 may be separate pieces that are rigidlyconnected to one another.

The first liner 12 is positioned within a pipe 20 and has a length thatis just a fraction of the length of the pipe 20, as best illustrated inFIG. 3. The sleeve 22 of the first liner 12 has an outer diameter thatis slightly less than an inner diameter of the pipe 20. The first liner12 may be formed from metals or plastics.

The second liner 14 is substantially identical to the first liner 12 andtherefore will not be described in detail.

The first pipe flange 16 is of generally annular disc shape with aninner surface 27 and an opposing outer surface 29 with plurality offastener openings 28 formed through the two surfaces 27, 29 atpredetermined rotational angular locations. An embodiment of the firstpipe flange 16 includes six fastener openings 28 positioned atrotational angle intervals of approximately 60 degrees. The first pipeflange 16 further includes an inner edge and a radially-spaced outeredge along which there may be features such as flat edges, cut outs, orthe like to provide alignment during the joining process or to provideother functions.

The first pipe flange 16 further includes a plurality of raised plateaus30 and a plurality of insets 32, as seen in FIGS. 2 and 5. Each plateau30 is positioned on the outer surface 29 of the first pipe flange 16 andincludes raised material with a generally planar top surface that has aheight above the outer surface 29. The perimeter of each plateau 30 mayhave a U shape, although square, rectangular, or other shapes arepossible. Each inset 32 is positioned on the inner surface 27 of thefirst pipe flange 16 and may include a recess that has a depth below theinner surface 27. Similar to the plateau 30, the perimeter of each inset32 may have a U shape, although square, rectangular, or other shapes arepossible. The plateaus 30 and the insets 32 are aligned with one anothersuch that each plateau 30 is aligned on the outer surface 29 with arespective inset 32 on the inner surface 27. Typically, the plateau 30and inset 32 combinations are positioned on the first pipe flange 16 tointersect the outer edge or circumference thereof and spaced apart fromone another. In addition, each plateau 30 and inset 32 combination arealigned with a fastener opening 28, such that a fastener opening 28extends from each plateau 30 to its aligned inset 32. An exemplary firstpipe flange 16 may include six plateau 30, inset 32, and fasteneropening 28 combinations positioned at rotational angle intervals ofapproximately 60 degrees. In other embodiments, the first pipe flange 16may have greater or fewer plateau 30, inset 32, and fastener opening 28combinations. The first pipe flange 16 may be formed from metals orplastics. The plateau 30 and inset 32 combinations may be formed bymolding, machining, tooling, or similar processes.

The second pipe flange 18 may be substantially identical to the firstpipe flange 16 and therefore will not be described in detail.

Referring primarily to FIGS. 1 and 3, the joint assembly 10 has astructure as follows. The first pipe flange 16 is coupled to one end ofa first pipe 20A, while the second pipe flange 18 is coupled to one endof a second pipe 20B. In some embodiments, each pipe flange 16, 18 isrigidly connected to the end of a pipe 20 by using techniques such aswelding or through the use of adhesives. In other embodiments, each pipeflange 16, 18 may include threads on its inner circumferential edge,while one end of each pipe 20 may include threads on its outercircumferential edge. Each pipe flange 16, 18 is coupled to one end ofeach pipe 20 by screwing one onto the other. In still other embodiments,each pipe 20 is formed to include one pipe flange 16, 18 coupled to eachend thereof, such that one pipe 20 and two pipe flanges 16, 18 are amonolithic unit.

Each pipe flange 16, 18 is coupled to one end of each pipe 20 such thatthe outer surface 29 of each pipe flange 16, 18 faces away from the pipe20. And the inner surface 27 of each pipe flange 16, 18 is adjacent tothe pipe 20 and faces the pipe 20. In general, and to form a largersystem, each pipe 20 may have a pipe flange, such as pipe flanges 16,18, coupled to each end thereof.

The first liner 12 is positioned within one end of the first pipe 20Asuch that the outer surface of the sleeve 22 faces the inner surface ofthe pipe 20, and the inner surface 23 of the liner flange 24 faces theouter surface 29 of the first pipe flange 16. The inner surface 23 ofthe liner flange 24 contacts at least a portion of the outer surface 29of the first pipe flange 16. Each cutout 26 of the liner flange 24 isaligned with a successive one of the plateaus 30 on the outer surface 29of the first pipe flange 16, and wraps around a portion of the plateau30. In addition, the outer edge of the first liner 12 extends radiallyoutward beyond an inner edge of each plateau 30. The second liner 14 ispositioned within one end of the second pipe 20B in a substantiallyidentical fashion as the first liner 12 within the first pipe 20A.

The first and second pipes 20A, 20B are axially aligned and the firstpipe 20A abuts the second pipe 20B such that the outer surface 25 of theliner flange 24 of the first liner 12 contacts the outer surface 25 ofthe liner flange 24 of the second liner 14. And each plateau 30 of thefirst pipe flange 16 faces a corresponding one of the plateaus 30 of thesecond pipe flange 18. In addition, the fastener opening 28 on eachplateau 30 of the first pipe flange 16 aligns and pairs with thefastener opening 28 on the corresponding plateau 30 of the second pipeflange 18. One fastener, such as a screw and a bolt, is positionedwithin each fastener opening 28 pair. The bolt is tightened on the screwof each fastener such that each plateau 30 of the first pipe flange 16contacts the corresponding one of the plateaus 30 of the second pipeflange 18—thereby forming a tight seal 34 between the outer surface 25of the liner flange 24 of the first liner 12 and the outer surface 25 ofthe liner flange 24 of the second liner 14, as seen in FIG. 3.

Having each bolt tightened until each plateau 30 of the first pipeflange 16 contacts the corresponding one of the plateaus 30 of thesecond pipe flange 18 ensures that uniform pressure is applied acrossthe area of the inner surface 23 of each liner flange 24. Hence, uniformpressure is applied to the seal 34 formed between the two liner flanges24 as well.

The liner flange 24 of each liner 12, 14 has a thickness, T, between theinner surface 23 and the outer surface 25, as seen in FIG. 4. Eachplateau 30 of the pipe flanges 16, 18 has a height, H, above the outersurface 29 of the pipe flange 16, 18, as seen in FIG. 5. Generally, theheight H of each plateau 30 is approximately equal to the thickness T ofthe each liner flange 24 to ensure nominal, adequate pressure on theseal 34 formed between the two liner flanges 24. Furthermore, the heightH is typically the same value for each plateau 30, and the thickness Tis typically the same value for each liner flange 24. Varying the heightof the plateaus 30 varies the pressure applied to the seal 34 betweenthe two liner flanges 24. If the pressure on the seal 34 between the twoliner flanges 24 needs to be increased to be greater than the nominalpressure, usually the height H is decreased to be less than thethickness T, although it is possible that the thickness T is increasedto be greater than the height H. Alternatively, if the pressure on theseal 34 between the two liner flanges 24 needs to be decreased to beless than the nominal pressure, usually the height H is increased to begreater than the thickness T, although it is possible that the thicknessT is decreased to be less than the height H.

Another embodiment of the current invention may provide a joint assembly100 as shown in FIG. 6. The joint assembly 100 may be utilized withpipes 20A, 20B and includes the first and second pipe liners 12, 14,substantially identical to those described above. The joint assembly 100further includes first and second pipe flanges 116, 118. In contrast tofirst and second pipe flanges 16, 18, each pipe flange 116, 118 does notinclude the plateaus 30 and the insets 32. Instead, each pipe flange116, 118 includes an annular recess 136 on an outer surface 129 adjacentto an inner edge of the flange 116, 118. As seen in FIG. 7, the recess136 has a depth D roughly equal to the thickness T of the liner flanges24. The recess 136 may be formed by molding, machining, or the like.Each pipe flange 116, 118 also includes a plurality of fastener openings128 extending from an inner surface 127 of the flange 116, 118 to theouter surface 129. The fastener openings 128 are positioned atrotational angle intervals, or circumferentially spaced along a circularpath, in the vicinity of the outer edge.

The joint assembly 100 has a structure that is similar to the jointassembly 10. The pipe flanges 116, 118 are coupled to the pipes 20A, 20Bin the same fashion as discussed above. The first and second liners 12,14 are positioned within the pipes 20A, 20B as discussed above, suchthat the liner flange 24 of the first liner 12 is positioned within therecess 136 of the first pipe flange 116 and the liner flange 24 of thesecond liner 14 is positioned within the recess 136 of the second pipeflange 118. The outer surface 25 of the liner flange 24 of the firstliner 12 contacts the outer surface 25 of the liner flange 24 of thesecond liner 14. And at least a portion of the outer surface 129 of thefirst pipe flange 116 contacts at least a portion of the outer surface129 of the second pipe flange 118.

Yet another embodiment of the current invention may provide a jointassembly 200 as shown in FIG. 8. The joint assembly 200 may be utilizedwith pipes 20A, 20B and includes the first and second pipe liners 12,14, substantially identical to those described above. The joint assembly200 further includes first and second pipe flanges 216, 218. Like thepipe flanges 116, 118, each pipe flange 216, 218 does not include theplateaus 30 and the insets 32. Instead, each pipe flange 216, 218includes an outer annular recess 236 on an outer surface 229 adjacent toan inner edge of the flange 216, 218 and an inner annular recess 238 onan inner surface 227 adjacent to an outer edge of the flange 216, 218.The inner recess 236 has a depth D roughly equal to the thickness T ofthe liner flanges 24. As seen in FIG. 9, the outer and inner recesses236, 238 may be formed by molding, machining, pressing, punching, orother forming techniques. Each pipe flange 216, 218 also includes aplurality of fastener openings 228 extending from the inner surface 227of the flange 216, 218 to the outer surface 229. The fastener openings228 are positioned at rotational angle intervals, or circumferentiallyspaced along a circular path, in the vicinity of the outer edge.

The joint assembly 200 has a structure that is similar to the jointassembly 10. The pipe flanges 216, 218 are coupled to the pipes 20A, 20Bin the same fashion as discussed above. The first and second liners 12,14 are positioned within the pipes 20A, 20B as discussed above, suchthat the liner flange 24 of the first liner 12 is positioned within theouter recess 236 of the first pipe flange 216 and the liner flange 24 ofthe second liner 14 is positioned within the outer recess 236 of thesecond pipe flange 218. The outer surface 25 of the liner flange 24 ofthe first liner 12 contacts the outer surface 25 of the liner flange 24of the second liner 14. And at least a portion of the outer surface 229of the first pipe flange 216 contacts at least a portion of the outersurface 229 of the second pipe flange 218.

Although the invention has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A joint assembly for joining two pipes together, thejoint assembly comprising: first and second liners, each liner includinga sleeve and a liner flange, the liner flange coupled to one end of thesleeve, the first liner configured to be positioned within a first pipeand the second liner configured to be positioned within a second pipe;and first and second pipe flanges, each pipe flange of generally annulardisc shape with an inner surface and an opposing outer surface includinga plurality of circumferentially spaced plateaus positioned thereon,each plateau having a height above the outer surface, the first pipeflange configured to be coupled to one end of the first pipe and thesecond pipe flange configured to be coupled to one end of the secondpipe, the first and second pipe flanges configured to couple to oneanother such that each plateau on the first pipe flange contacts acorresponding plateau on the second pipe flange, wherein each linerincludes a plurality of cutouts, each cutout having a generally arcuateconcave shape and being circumferentially spaced along an outer edge ofthe liner flange, each cutout configured to align with a successive oneof the plateaus of one pipe flange.
 2. The joint assembly of claim 1,wherein an inner surface of the liner flange of the first liner isconfigured to contact at least a portion of the outer surface of thefirst pipe flange and an inner surface of the liner flange of the secondliner is configured to contact at least a portion of the outer surfaceof the second pipe flange.
 3. The joint assembly of claim 1, wherein anouter surface of the liner flange of the first liner is configured tocontact an outer surface of the liner flange of the second liner to forma seal between the first pipe and the second pipe.
 4. The joint assemblyof claim 3, wherein the liner flange of each of the first and secondliners has a variable thickness and when the thickness is approximatelyequal to the height of each plateau, a nominal pressure is applied onthe seal between the first pipe and the second pipe.
 5. The jointassembly of claim 4, wherein when the liner flange of each of the firstand second liners has a thickness that is less than the height of eachplateau a greater than nominal pressure is applied on the seal betweenthe first pipe and the second pipe.
 6. The joint assembly of claim 4,wherein when the liner flange of each of the first and second liners hasa thickness that is greater than the height of each plateau a less thannominal pressure is applied on the seal between the first pipe and thesecond pipe.
 7. The joint assembly of claim 1, wherein each pipe flangeincludes a plurality of insets positioned at rotational angles on theinner surface thereof, each inset having a depth below the inner surfaceand aligned with a successive one of the plateaus.
 8. The joint assemblyof claim 1, wherein each pipe flange includes a plurality of openingsfrom the inner surface to the outer surface, each opening positionedwithin a region occupied by a successive one of the plateaus andconfigured to receive a successive one of a plurality of fasteners.
 9. Atwo pipe assembly comprising: first and second pipes axially alignedwith one another; first and second liners, each liner including a sleeveand a liner flange, the liner flange coupled to one end of the sleeve,each liner flange including an inner surface adjacent to the sleeve andan outer surface facing away from the sleeve, the first liner positionedwithin the first pipe and the second liner positioned within the secondpipe, the first and second liners facing each other such that the outersurface of the first liner contacts the outer surface of the secondliner to form a seal between the first pipe and the second pipe; andfirst and second pipe flanges, each pipe flange of generally annulardisc shape with an inner surface and an opposing outer surface includinga plurality of circumferentially spaced plateaus positioned thereon,each plateau having a height above the outer surface, the first pipeflange configured to be coupled to one end of the first pipe and thesecond pipe flange configured to be coupled to one end of the secondpipe, the first and second pipe flanges configured to couple to oneanother such that each plateau on the first pipe flange contacts acorresponding plateau on the second pipe flange.
 10. The two pipeassembly of claim 9, wherein the inner surface of the liner flange ofthe first liner contacts at least a portion of the outer surface of thefirst pipe flange and the inner surface of the liner flange of thesecond liner contacts at least a portion of the outer surface of thesecond pipe flange.
 11. The two pipe assembly of claim 9, wherein theliner flange of each of the first and second liners has a variablethickness and when the thickness is approximately equal to the height ofeach plateau, a nominal pressure is applied on the seal between thefirst pipe and the second pipe.
 12. The two pipe assembly of claim 11,wherein when the liner flange of each of the first and second liners hasa thickness that is less than the height of each plateau a greater thannominal pressure is applied on the seal between the first pipe and thesecond pipe.
 13. The two pipe assembly of claim 11, wherein when theliner flange of each of the first and second liners has a thickness thatis greater than the height of each plateau a less than nominal pressureis applied on the seal between the first pipe and the second pipe. 14.The two pipe assembly of claim 9, wherein each liner includes aplurality of cutouts, each cutout having a generally arcuate concaveshape and being circumferentially spaced along an outer edge of theliner flange such that each cutout aligns with a successive one of theplateaus.
 15. The two pipe assembly of claim 9, wherein each pipe flangeincludes a plurality of insets positioned at rotational angles on theinner surface thereof, each inset having a depth below the inner surfaceand aligned with a successive one of the plateaus.
 16. The two pipeassembly of claim 9, wherein each pipe flange includes a plurality ofopenings from the inner surface to the outer surface, each openingpositioned within a region occupied by a successive one of the plateausand configured to receive a successive one of a plurality of fasteners.